Pump



Aug.` 5 1924.

M. BucHERER PUMP Filed June 23, 1922 2 Sheets-Sheet 2 miliiiiii'm fiillll f @man IIIII l ZZ-orney- Patented ug. 5, 1924.

UNITED". STATES PATENT cFFIcE.

PUMP.

; Application filed June 23, 1922. Serial No. 570,421.

To all whom t may concern.: A

Be 1t known that I, MAX BUoHnnnR, a citizen of Germ'any, residing at Berlin- Reinickendorf-Vtest, Germany, have invent' ed certain new and useful Improvements in Pumps, for which I have filed application in Germany, October 20, 1916, of which the following is a specification.

My invention refers to pumps and more especially to feed pumps or injection pumps for` liquid fuelssuch as benzine and the like serving for driving internal combustion engines. j

It is an object of my invention to provide a pump capable of injecting under pressure or of atomizing in the combustionr chamber or cylinder or the like or'in the pipe leading thereto minute quantities of a liquid such as liquid fuel and which may amount to not-.more thanthe fraction of a drop in each case, this being done with an extraordinarily high speed and eXactness.

Itis a further object of my invention to Y provide a pump which is capable of conveying always the same quantity of liquid such as fuel independently of the number of rotations of the engine shaft and without regard to the minuteness of the quantities of fuel fed in rapid succession.

It is a further object of my invention to provide a pump which will convey liquid with lthe least expenditure of power and nevertheless with great speed and absolute uniformity and which consists of so few and so simply actuated parts that it will not easily get out of order but will remain permanently operative.

These and other ob'ects of my invention will appear from the following description thereof together with the drawings which illustrate my invention by way ofexample as embodied in a fuel feed pump for internal combustion engines.

l wish it to be understood that my invention is neither restricted to the details of construction nor te Vthe combination of all the parts disclosed in the drawings, n or to pumps serving for the supply of fuel, for themeans of imparting motion as well as other parts of mechanism shown in the drawing might as well be replaced by similar parts and the pump might as Well beV used for other liquids than lfuel without departing vfrom the spirit of my invention.V

In the drawing:

AFig. 1 is a vertical section, partly in elevation, of the pump casing and the pump properl on the line 1-1 in Fig. 2 as viewed from the left in Fig. 2.

Fig. 2 is a vertical section at right angles to the one in Fig. 1 taken on the line 2.--2 in Fig. 1.

Fig. 3 is a longitudinal section of the fuel feed system taken on the line 3-3, the pump casing cover being shown in elevation.

Fig. 1 is a plan view from below of the driving mechanism.

Fig. 5 is an elevation and Fig. 6 is a vertical section of one of a pair of perforated discs disposed in the pump casing and serving for limiting the movements of the diaphragm arranged between them.

Fig. 7 is a diagram drawn to a reduced scale and disclosing an arrangement of the pump as used for instance in connection with motor cars together with the fuel tank placed under constant pressure.

Referring to the drawing, 1, 2. is the pump casing in two parts, part 1 being fixed by aid of threaded bolts on top of a box 3 surrounding the driving mechanism. Part 1 of the pump casing enclosing the pistons has a chamber 4f of T-shaped section which is separated from part 2 by a portion or diaphragm 5 capable of deformation. rlhis diaphragm which may consist of some. suitable more or less elastic material, amongst others thin sheet metal, is fixed in position between a pair of perforated discs 6 vaulted in opposite direction, such discs being held `with their edges between parts 1 and 2 of the pump casing. The two perforated discs 6 allow the middle portion of the diaphragm 5 to be moved to either side so as to apply itself againstone of these discs which thus serve to prevent the diaphragm from being overstrained or destroyed by an undue pressure which might arise.

In the solid rear wall of part 1 of the casing there are arranged the cylindrical borings 7, and 8 serving to guide two pistons 9 and 10 of small diameter which are reciprocated therein byl the driving mecha nism `tol be described further below. The chamberf and that portion of the cylindrical borings 7 and 8 that is not occupied vby the pistons 9 and 10 is filled with a liquid suchY as oil, glycerine or the like, while the chamber 11 in the part 2 of the casing is filled with the liquidsuch as liquid fuel to be conveyed.

chambers l and 11 of the pumpcasing as'V well as the fuel supply and discharge pipes connected therewith are permanently placed under constant pressure. In applying this pump to stationary uses this may be effected for instance by placing the fuel tank high above the pump, thus providing a .high

column of liquid fuel which exerts pressure on the fuel contained in chamber 1l. In applying my invention to moveable uses such as motor vehicles I prefer employing a container such as let filled with gas or air' under pressure andV which is connected with the interior of the fuel tank 12 by a pipe 13, a reducing valve being inserted between the container 14 and the pipe 13 as usual. The gas pressure acting on the liq- C uid in the fuel tank 12 acts towards placing the liquid in chamber 11 under constant pressure.

The fuel is fed from the fuel Vtank 12l throughan admission pipe 16 into the head portion 17 ofthe pump which is provided with a longitudinal boring 18 for the admission and a Vlongitudinal boring 19 for the diaphragm nels'l and 25.

V22 loaded with a spring 21.

theldisclharge of the fuel. The admission boring 18 extends upwards in the Vmiddle portion of the head 17 and this upwardly extending part 2O is closed by a ball valve From the valve chamber 23 a boring 24 leads to the fuel discharge boring 19 which has the pipe 25 leading to the cylinder or the like connected to it. Near the end of this pipe there is again arranged a ball valve 26 pressed on its seat by a spring 27.

F rom the point of intersection of the borings of channels 19 and 24 a downward directed channel 28 leads to the chamber 11. Provided that Vthe spring' load lasting on each of the two ball valves 22 and 26 be equal to the gas pressure lasting on the fuel to be conveyed, so long as the two pistons 9 and 10 give away to one another to an equal extent, in other words, if the two pistons have equal diameters and move with equal Velocity in opposite directions,

will flow through the chan- VHowever, if the two pistons 9 and 10 are imparted an unequal motion, one of them, such as piston 10, ending its stroke sooner than the other piston, in other words, if piston has a shorter stroke than piston 9, then the substantially constant quantity Vof* oil or glycerinV in the chamber 4t will be forced against the diaphragm. This will cause this latter to bulge tion and no fuel lfirst 'displaced the; 'difference is held in its normal posi lifted from its seatV andi-some -fuel will be V YforciblyV dischargedfrom the channel 25. On 'the two pistons 9 and 10 now moving in opthe working piston 9 is Abetween the strokes of the two pistons and only there-Y after the .coml'aensating piston 10i will rise.-

posite direction,

As the working piston- Qstarts on its return l stroke, the entire quantity of oil or glycerin v is free to move back into the chamber LtV and, in consequence thereof, the diaphragm will return to its normalV positionQ In chamber 11 there is now Vroom fora fresh quant`ity of fuel equal toftherquantity ejectedthrough the dischargevalve.V The gas presisure lasting on the admission valver22Y causes the fuel in the pipe 16 to lift'the valveA 22 and the fuelin up under pressure.

sa I `chamber 11 Vis, thus lledrv Asfwill be seen from Vthe foregoing descriptio'n,my novel pump incontradistinction tok other pumps does not draw liquid into the pump chamber by suction, but the substantially constant Vpressure acting on the Y liquidin the feed pipe well, as soon as, in consequence of some of the liquid.v in the pump. chamber A11 having beenV ejected through the discharge valve, the pressure diminishes, slightly fill up4 the liquid Vinthe Y i pump chamber. tile Vor gas .containing liquid,'such` as liquid fuel, this mode of working entails the great advantage that the liquid to bejconveyed is permanently subjected to a substantially equal pressure, whereby a volat-ilization of the liquid or the separation of air, gases or vapours and the formation of bubbles connected therewith is absolutely prevented from taking place. Obviously, a formation of bub-` bles would cause the conveying -of liquid to comel to a standstill, inasmuchV as the pistons in moving Yup andY down would merely alternately compress the little quantity of air, gas or vapour and.v allow expand again.V f

In the modification the pistons 9 and 10 are positivelyY actuated by a double arm rock leverV 29,330, rocking about a horizontal neath the pistons, said lever causing the pistons to rise againstthe action'ofsprings 33 tending to holdsthemin depressed 'rpo-Q shown in the drawing, Y

`W'ith regard toeasily vola- 1 l axle 28 under- Y y Y piston 10.V l However, the Y end and movable in cylindrical Vsleeves 32P V.being inserted between the4 arms of the lever and the 'pistonsv and adapted toreciproeate vertically against theaction:ofthe-springs; 33. The sleeves `are in contact withV thel Y Awalls of the borings'34 of the pump casing.f

The members 31 are linked to the pistons 9 and 10, a link 35 having its ends hollowed iiXed on the horizontal driving shaft 42 by aid of a coil spring 43 having its other end attached to a screw bolt 44 arranged in the bottom of the box 3.

The cam of the eccentric 4l is so shaped that the rock lever alternately gives way and presses upwards respectively one or the other member 31. If the arm of the rock lever moves downwards, then the respective member is pressed downwards by its spring 33 and pulls its piston along. -On the other hand, the positive pressure of the arms of the rock lever causes the pistons to alternately rise against the action of springs 33.

The descending movement of the member carrying the compensating piston 10 is limited by a stop which in the modification disclosed in the drawing has the form of a threaded spindle 45 guided in a nut 46 and a stufling box 47 at the bottomof box 3 and the upper end of which extends into the path of the respective member, so that, as this member meets the stop, the down stroke of the compensating piston comes to an end, while the working piston is free to still iinish its upward movement. By turning the spindle 45 the downstroke of the compensating piston 10 and with it thequantity to be conveyed by the pump per stroke can be varied within wide limits.

In order that the oil or the like contained in the chamber 4 be filled up again in case that some of it should escape from the chamber past one of the pistons 9 or 10 an oil filled tube 48 is arranged in the head of the pump casing, said tube being closed by a non return valve 49 placed Vunder the pressure of a spring equalling the pressure prevailing in the interior of the pump. As soon as the quantity of oil in the chamber 4 should di minish unduly, the valve 49 will be somewhat relieved and will allow the-'same quantity of oil to enter chamber 4.A

As described above, my novel pump does not convey any liquid during the greater part of the piston stroke. The ascending piston 9 merely displaces the oil or the like within the chamber 4 and forces it into the I boring or cylinder of the receding piston 10.

Only after this latter piston has been brought to a standstill by meeting the stop, the short portion of the upward stroke which is still left for the working piston 9, causes a sudden ejection of a more or less minute quantity ofliquid subjected to constant pres sure.

l/xhile inordinary high speed pumps the valves, owing to the severe strains placed thereon, are subject to early destruction, the valves in the novel pump according to the present invention are merely acted upon by the pressure of their springs which is only slightly higher than the gas pressure acting on the liquid. valves in opening have to overcome and are forced back into their seats only by this small dierence in pressure so that, although the pump be run with more than 1000 revolutions per minute, the valves can liever' be 1 overstrained and will last almost indefinitely.

The pistons 9 and 10 being permanently lubricated by the oil in the chamber 4 do not even come in contact with the cylinder walls, but are continually covered with a film of oil wherebv friction is reduced to a minimum.

I claim l. A pump comprising in combination, a pump casing, means for holding said casing under constant increased pressure, a piston movable relatively to the interior of said casing vand means for causing said pis ton to convey liquid under pressure only during the latter part of its conveying stroke. e

2. A pump comprising al piston and means for causing said piston to convey liquid under substantially constant pressure only near the end of its conveying stroke.

3. A pump comprising in combination, a pump casing, a diaphragm within said casing dividing it in two chambers, one of said chambers being filled with a substantially constant quantity of a liquid, admission and discharge ports in the other chamber for the liquid to be conveyed, two pistons movable in said first chamber, and means for forcing one of said pistons into said first chamber, so as to cause the other piston to give way in opposite direction, said other piston havinga shorter stroke than said first piston.

4. A pump comprising in combination, a pump casing, a diaphragm within said casing dividing it in two chambers, one of said chambers being filled with a substantially constant quantity of a liquid, admission and discharge ports in the other chamber for the liquid to be conveyed, two pistons movable in said first chamber, means for forcing one of said pistons into said first chamber, so as to cause the other piston to give way in opposite direction and displaceable means for arresting said other piston, before said rst piston has completed its stroke.

5. A `pump comprising in combination, a pump casing, a diaphragm within said casing dividing it in tw'o chambers, one of said In consequence thereof the return valves closing said ports, means for holding;` said chambers, said ports-,and said valves under a suibstantially constant 1n- 'creased pressure slightly inferior to theY valve pressure and means for displacing the substantially constant quantity of liquid in said first chamber, so as to force said diaphragm towards said other chamber and therebyto cause one of said valves'to open.

6.Y Apump comprising in Combination, a pump easing, a diaphragm Within said casing dividing it in two chambers, one of said ehanrbers being iilled With .a substantially constant quantity of liquid, admission and 'discharge ports in said otlierchamber, non

returnvalves closing said port-s, means for vholding said chambers, said ports and said valves under a substantially constant: increased pressure slightly inferior to the valve pressure, two pistons movable irivsaid first chamber, and means for forcing one of said pistons' into said rst chambeiyso as to cause the other piston to give Wayinoppo-1 site direction, said otherrpiston having a shorter stroke than-said lirst piston.

7. A pump comprising iii-combination, a

pump casing,fa diaphragm Within said yeasingdividing itin tivo Chambers, one of said holding said chamber, said ports and saidV valves under a 'substantially const-ant 1ncreasedv pressure slightly inferiorV to the valve pressure, two Vpistons movable'in said f first ehambenmeans vfor forcing one. of said 'pistons into said first chamber, so as to cause the other piston to give Way in oppo-gY `vsite direction, and means for` arresting said said iirst pistonY has Y other piston, before completed its stroke. f

`In testimony whereof I aiiix my sionature. .Y Y i MAX BUCHERER. 

